The facts were held Tuesday in Saint-Laurent-Blangy in the Pas-de-Calais.
At about 11: 00, a mother of a family was crossing the pedestrian crossing with her baby when a car came along at a brisk pace, and has struck them.
The child, 18-month-old, was pinned under the vehicle and it took the intervention of four persons to lift the machine and hold the baby.
The two victims were transported by helicopter to the hospital where the mother of 38 years died Wednesday from his injuries. Her baby was operated on and his prognosis is not engaged.
As the driver of the vehicle, she was placed in police custody. Any door to believe that she was speeding because she was travelling at a high speed in a zone limited to 30 km/h.